Circuit breaker



SePt- 14 1948- o. G. KILLIAN ET AL 2,449,486'

CIRCUIT BREAKER Filed March 15, 1945 mi... i .,f/

Patented Sept. 14, 1948 2.449.488 vCIRCUIT BREAKER Orvel G. Killian, Wapakoneta, and Bascum O. Austin, Lima, Ohio, asslgnors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application Maren 15, 1945, serial No. 582,894

This invention relates to improvements in circuit breakers, and although not limited thereto. the invention relates particularly to overload circuit breakers for airplanes and the like.

A primary object o! the invention is to minlmize the space requirements. and. consequently, the weight-of such a device, while insuring trustworthy operatlon thereof under all conditions.

Another object is to provide a manually controllable overload circuit breaker which is nontrip free, to provide for attainment of an improved and desirable result.

vAnother object is to provide a circuit breaker oi the aforementioned character which will withstand severe vibration without accidental tripping thereof or arcing at its contacts.

Another object is to provide a circuit breaker of improved construction embodying an operating lever and associating therewith resilient means which continually bias the contact means either in'their separate or engaged positions.

Another object is to `provide an improved circuit breaker of the non-trip-iree type in which the contact structure is of improved construction.

Another object is to provide a circuit breaker which will perform in a normal manner under maximum flight altitude conditions.

Another object is to provide a circuit breaker which is substantially unaiected by variations in ambient temperature or pressure conditions.

Another object is to provide an overload circuit breaker, the various parts of which are much smaller and more compactly arranged than those of circuit breakers of similar capacity heretofore known.

Another object is to provide an overload circuit vbreaker whose frontal area is the same as that of switches, now standard in aircraft servicc.

Another object is lto provide a' manually controlla-ble overload circuit breaker consisting oi a group of elementsl most of which are common to such devices having a -Wide range of different capacities.

Another object is to minimize the number of dlerent parts required to ailord thedesired range of variation in the circuit controllingcapacities of such devices.

Another object is to provide a circuit breaker which may be manually closed and/or held closed regardless of overload conditions.

Another object is to provide a stationary dusttight enclosure for the operating elements of such a circuit breaker.

Another object is to provide novel means including a simple operating lever for operating the breaker mechanism and for simultaneously resetting the overload mechanism after tripping of the latter.

5 Claims. (Cl. 200-116) Another object is to provide an improved circuit breaker construction of the non-trip-iree type in which the construction is made very rigid by utilizing an improved frame construction upon which the several parts of the breaker may be mounted.

lAnother object is to provide an improved circuit breaker having improved cam means for insuring that the contacts will be either in the open or closed positions.

Further objects and advantages of our invention will be readily apparent upon a reading oi' the following specification taken in conjunction with the drawing in which,

Figure 1 is a vertical sectional view through an improved circuit breaker embodying our invention, the parts being shown in the closed circuit position.

Fig. 2 is a fragmentary sectional view taken substantially along the line I I-II oi Fig. l.

Fig. 3 is a View similar to Fig. 1, but showing the disposition of the several parts in the open circuit position of the interrupter.

Fig. 4 is a detail view of the bimetallic arm used to provide overload protection.

Fig. 5 is a plan view of the ybimetallic arm construction.

Fig. 6 is a perspective `view oi a detail used in the movable contact construction.

Fig. 7 is a perspective view of the movable contact.

Fig. 8 is a perspective view of the improved cam means which is employed in our invention, and

Fig. 9 collectively shows the improved trip lever of our invention.

Referring to the drawing. and more particu-l larly to Fig. 1 thereof, the reference numeral I designates a casing which is preferably molded out of a suitable insulating material. The casing i has its upper-.portion enclosed by an insulating plate 2, the latter, in turn, being covered by a metallic plate 3 having self-locking nuts 4 which are rigidly secured to the casing i. The top portions 5 of the self-locking nuts 4 yare spun over the surface of the metallic plate 3. vThe metallic plate .3 preferably has engraved thereon of the circuit.

the ampere and voltage capacity breaker.

Disposed within the casing i is a. U-shaped metallic frame 6 which has at its upper end pro- -Iour corners of the outer metallic plate 3.

i Extending through the vertical side portions I, i0 of the U-shaped frame 8 is a pin I i upon which is mounted an operating lever, generally desigpreferably composed of metal which has its lower end threaded at I4 to threadedly engage a curved metallic member I5, the latter having at its ends downwardly projecting hooks, not shown, which secure it into place within a molded member I6. Preferably at the upper end of the handle portion I3 is a screw I1 having a luminescent tip so as to be visible in the dark.

Also embedded partially in the molded member I6 is a U-shaped member IB having upwardly extending leg portions I9, 20 with the upper ends thereof having oistanding lug portions 2| which serve to anchor the upper end xedly in place within the molded member I6. The leg portions I9, 2U of the U-shaped member I8 are slotted as at 22, 23, the purpose for which will appear more clearly hereinafter. The bight portion 24 of the U-shaped member I8 has two slots 25, 26 formed therein which serve to engage the lower hook portion 21 of a tension spring 28, the upper end of which has its hook portion 29 curved about a third pin 3D which passes through the slots 22, 23 of the U-shaped member I8.

At the outer ends of the pin 30 are loosely disposed two cam rollers 3| having a conguration more clearly shown in Fig. 8. The two cam rollers 3| constantly engage the upper portions 32 of the two leg portions 33, 34 of a movable contact member of U-shaped configuration generally designated by the reference numera-l 35. Preferably the bight portion 36 of the movable contact member 35 has a contact tip 31 rigidly secured thereto by spot welding.

The arms or legs 33, 34 of the movable contact 35 have apertures 38 provided therein which engage inwardly extending pins 38, 40 which pass inwardly through the side portions 9, I8 of the U-shaped metallic frame 6 in a manner more clearly shown in Fig. 2.

It will be observed that in the fully open and fully closed positions of the breaker, as shown in Figs. 1 and 3, the cam rollers 3| constitute a pair of cams which serve as resilient means for biasing the contact means in either the fully opened or fully closed positions thereof. It will be observed that the tension spring 28 constantly biases the pin 3lI toward the lower extremity of the operating lever I2.

The overload release means for the circuit breaker will now be described. The overload release means is provided in the form of a bimetallic arm 4I which bends in a counterclockwise dlrection about its stationary portion to permit a latch portion 42 thereof to release a trip lever 43 which has a configuration more clearly shown ln Fig. 9. The trip lever 43 has an aperture 44 provided therein which serves as a bearing for the pin I I. Consequently, the trip lever 43 is mounted on the same pin II which supports the operating lever I2 with the result that both the trip lever 43 and the operating lever I2 have the same 4 I. It will'be observed that a recess 49 is provided in the molded member I6, as shown in Fig. 2, to accommodate the rotative movement of the trip lever 43. The trip lever 43 has a latch portion 50 which, in the normal operation of the breaker, engages a latch bar 42, the latter being secured by rivets 5| to the bimetallic arm 4|. Preferably the rivets 5| also secure a bimetallic shield 52 composed of a suitable insulating material, such as mica. The lower end of the bimetallic arm 4| is secured in place by a screw 53 which passes upwardly through the bottom 54 of the casing to threadedly engage a horizontal portion 55 of the bimetallic arm 4I. Also secured as by welding to the horizontal portion 55 is a stationary contact tip 56 which cooperates with the contact tip 31 of the movable contact 35.

The bimetallic arm 4| is of bifurcated configuration as shown by the dotted lines in Fig. 4, the leg portions thereof being designated by the reference numerals 58, 59. The screw 53 passes through the horizontal portion 55 of the leg portion 58 of the bimetallic arm 4|, whereas the terminal lug 51 is secured by a rivet 60 to a horizontal portion 6I of the leg portion 58 of the bimetallic arm 4|. The4 terminal lug 51 has an L-shaped portion 62 having a threaded aperture 63 formed therein which serves as the seat for a screw 64, the latter passing through a side wall 65 of the casing I. Two insulating plates 55a and 55h are positioned below the horizontal portion 55 to prevent shorting by the terminal lug 51.

A screw 66 passing through the opposite side wall 61 of the casing I secures in place a second terminal lug 68, the latter being welded to a flexible shunt 69, the upper end of which is welded as at 10 to the bight portion of the U-shaped metallic frame 6.

Thus, in the closed circuit position of the breaker the electrical circuit therethrough comprises terminal lug 68, flexible shunt 69, U-shaped ymetallic frame 6, pins 39, 40, side contact arms 33, 34, movable contact tip 31, stationary contact 56, leg portion 58 of bimetallic arm 4|, bight portion 1| of bimetallic arm 4|, leg portion 59 of bmetalllc arm 4I, iivet SII to the opposite terminal lug 51 of the breaker. Thus, the current passing through the breaker passes in series through the bimetallic arm 4I. Y

It will be observed that in the closed circuit position of the breaker, as shown in Fig. l, the tension spring 28 biases the cam rollers 3| down'- wardly against the upper portions 32 of the movable contact 35 to maintain the requisite co'ntact pressure between the movable contact tip 31 and the stationary contact tip 5l. Thus, although vibration may exist, still the tension of the tension spring 26 is sufficient to maintain the proper contact pressure in the closed circuit position of the breaker as shown in Fig. 1.

It will also be noted that the trip lever 43 is provided with. a shoulder 13 (Figs. 1, 3 and 9) which is engaged by an abutment 14 on the U- shaped member I8 to act as a stop for the operating lever I2 in the closed position of the circuit breaker. The abutment 14 comprises a pair of inwardly bent lug portions 15 integrally formed with the U-shaped member I8 and bent toward each other as shown more clearly in Fig.' .6.

To manually effect an opening operation of the breaker, the handle I3 is rotated in a counterclockwise direction about the pin II to thereby raise the cam rollers 3| against the downward biasing action exerted by the tensionspring 28.

When the downward force exerted by the cam rollers 3| passes to the right of the axis of rotation of the pivot pins 39, 40 so that the cam rollers 3i are brought to bear against the end portions 12 of the movable contact 35, then there will occur a snap opening action of the movable contact 35 to cause separating upward motion therei of away from the stationary contact 56.

Thus, it will be observed that also in the open .circuit position of the breaker as shown in Fig. 3, there again exists pressure exertedby the cam rollers 3l to forcibly maintain the movable contact 35 in its opened circuit position.

If, when the breaker is in the closed circuit position as shown in Fig. l, an overload exists in the electrical circuit controlled by the breaker, the bimetallic arm 4I, which carries the series current through the breaker, will flex toward the left to permit a release of the trip lever 43 to thereby permit the tension spring 46 to rotate the trip lever 43 about the pin II in a counterclockwise direction.

During the counterclockwise rotation of the trip lever 43, the shoulder portion I3 thereof moves the abutment'member 14 carried by the -movable contact assembly therewith to forcibly cause counterclockwise rotation of the operating lever I2 about the pin II. The vresulting opening operation during such an overload tripping operation is exactly the same as described above during a manually opening operation; con- -sequently, a further description thereof appears unnecessary.

It suffices to mention that during a subsequent closing operation the handle I3 is rotated in a clockwise direction about the pin II to carry not only the movable U-shaped member I8, but also lthe trip lever 43 in opposition to the tension spring 46. This clockwise rotation of the operating lever continues until the latch portion 50 of the trip lever 43 is again latched by the latch portion 42 of the bimetallic arm 4I. overload still continue in the circuit controlled by the interrupter, the breaker will again be opened upon a release of the handle I3. But should it be desired to maintain the contact means closed regardless of overload conditions, such a result may be obtained by forcibly maintaining the handle I3 in its closed position as shown in Fig. 1.

From the foregoing description, it will be apparent that the mechanism is hence non-trip free in operation inasmuch as the contact structure may be manually maintained closed regardless of overload conditions existing in the circuit controlled by the breaker.

It will be observed that different ampereV capacities of the breaker may be obtained merely by changing only the bimetallic arm 4I, the rest of the contact mechanism being the same for all current ratings. Thus, by merely changing the bimetallic arm 4I to one of a different load rating, the breaker may be thus adapted for different current carrying capacities.

It will also be apparent from the foregoing description' that the operating mechanism is extremely simple and compact in structure and provides therequisite operating pressure in both the opened and closed circuit positions of the breaker. It will also be apparent that there are few parts employed and that they may be formed from sheet metal strips stamped and bent to the proper coniiguration. l

Furthermore, the breaker construction is rigid inasmuch as the U-shap'ed metallic frame i being Should an an integral unit iixedly supports in place the several parts of the operating mechanism.`

It will also be noted that the assembly ofthe breaker is facilitated by the fact that the operating lever I2 may be separately assembled and easily positioned into place within the U-shaped metallic frame B. The movable contact 35 is also simple in construction and may easily be mounted upon the pins 39, 40, the latter being separately riveted in place on the leg portions 8, I0 of the metallic frame 6.

It will further be noted that the cam roller shaft 30 may easily move up and down in the slots 22, 23 during the opening and closing positions of the interruptor because of the fact that the cam rollers 3l are freely mounted on the cam roller shaft 30 and configuration is not changed during long operational life since new surface portions of the cam roller 3l constantly come into place. Also it will be observed that mechanical means are provided for producing pressure to open and close the breaker using a tension spring 28 which travels with the operating lever arm and is not swung around a ilxed point which would result in wear of the spring hook.

Although we have shownk and described a specie structure, it is to be clearly understood that the same was merely for the purpose of illustration and that changes and modifications may readily be made therein by thoseskilled in the art without departing from the spirit and scope of the appended claims. l

We claim as our invention:

1. In a circuit breaker, an operating lever, means pivotally mounting the operating lever,

said operating lever carrying two slotted leg por- `contact through the leg portions thereof; said spring urging said rollers into engagement with said leg portions to cause said movable contact to be rocked to open and closed circuit positions in response to rocking movement of said operating lever, a trip lever mounted for rotative movement, biasing means to bias the tripy lever into rotative movement, and overload release means to latch the trip lever in a normally stationary position, said trip lever when released moving said operating lever tothe open circuit position.

2. In a circuit breaker, a U-shaped frame, a pin extending across the frame. an operating lever pivotally mounted on said pin and movable to open and closed positions, a trip lever pivotally mounted on said pin, a second pin extending across the frame, a tension spring having one end secured to said second pin and having its other end secured to the trip lever to bias said lever to tripping position, the lower portion of the operating lever having two slotted legs, a third pin extending through the slots in the legs, two cam rollers mounted on the ends of said third pin, the lower ends of the slotted legs being connected -by a bight portion, a second tension spring having one end secured to the bight portion and having its other end secured to the third pin, pin means mounted by the frame, a bifursaid movable contact. the legs of. said movable contact extending on either side of the lower end of said operating handle and providing two substantially straight portions for receiving said cam rollers, said second spring urging said rollers into engagement with said straight portions of said movable contact to bias said movable contact to open position and to provide contact pressure when said movable contact is in closed position in accordance with the respective positions of said operating lever, and electroresponsive means normally restraining said trip lever and operable in response to overload current to release said trip lever, said trip lever when released actuating said operating lever to open Dosition.

3. In a circuit breaker, a U-shaped frame, a

vpin extending across the frame, an operating lever pivotally mounted on said pin and movable to open and closed positions, a trip lever pivotally mounted on said pin, a second pin extending across the frame, a tension spring having one end secured to said second pin and having its other end secured to the trip lever to bias said trip lever to tripping position, the lower portion of the operating lever having two slotted legs, a third pin extending through the slots in the legs, two cam rollers mounted on the ends of the third pin, the lower ends of the slotted legs being connected by a bight portion, a second tension spring having one end secured to the bight portion and having its other end secured to the third pin, a bifurcated movable contact pivotally mounted on said frame, a stationary contact cooperating with said movable contact, the legs of said movable contact extending on either side of the lower end of said operating handle and providing two substantially straight portions for receiving said cam rollers, said second spring urging said rollers into engagement with said straight portions of said movable contact to bias said movable contact to open position and to provide contact pressure when said movable contact is in closed position in accordance with the respective positions of said operating lever, and current responsive means including a bimetallic arm to normally latch the trip lever against movement, said current responsive means being operable in response to overload current to release said trip lever to permit the latter to actuate said operating lever to open position.

4. A circuit breaker comprising a. box-like casing of insulating material, a frame in said casing including at least a pair of spaced metal plates, an operating' lever pivotally mounted between said plates and having a portion extending exteriorly of said casing, a trip lever pivotally mounted on a common axis with said operating lever, a tension spring having one end secured to said frame and having its other end secured to said trip lever to bias said trip lever to tripping position, the lower portion of the operating lever having two slotted legs, a pin extending through the slots in said legs, two cam rollers mounted on the ends of said pin, the lower ends of the slotted legs being connected by a bight portion, a second tension spring having one end secured to said bight portion and having its other end secured to said pin, a preformed movable contact member of integral construction comprising a pair of parallel arm portions joined at one end by a transverse portion, means pivotally mounting the other ends of said arms to said frame, a contact tip carried by said transverse portion, a stationary contact carried by one wall of said casing for cooperation with said contact tip, said parallel arm portions having substantially straight upper surfaces extending to either side of their pivotal mounting for receiving said cam rollers, said second spring biasing said rollers into engagement with said straight surfaces to cause said contact member to be rocked about its pivotal mounting as said rollers traverse said surfaces from one side of said mounting to the other in responseto oscillating movement of said operating lever and thereby eilect opening and closing movement of said movable contact member with a snap action, and current responsive means including a bimetallic arm t0 normally latch the trip lever in predetermined position and operative to release said trip member upon the occurrence of overload conditions, and an abutment member carried by the operating lever and actuated by the trip lever when the latter is released by the bimetallic arm to move said operating lever to the open circuit position.

5. A circuit breaker comprising a box-like casing of insulating material, a frame in said casing including at least a pair of spaced metal plates, an operating lever pivotally mounted between said plates and having a portion extending exterlorly of said casing, the lower portion of the operating lever having two slotted legs. a pin extending through the slots in said legs, two cam rollers mounted on the ends of said pin, the lower ends of the slotted legs being connected by a bight portion, a tension spring having one end secured to said bight portion and having its other end secured to said pin, a preformed movable Contact member of integral construction comprising a pair of parallel arm portions joined at one end by a transverse portion, means pivotally mounting the other ends of said arms to said frame, a Contact tip carried by said transverse portion, and a stationary contact carried by one wall of said casing for cooperation with said contact tip, said parallel arm portions having substantially straight upper surfaces extending to either side of their pivotal mounting for receiving said cam rollers, said spring biasing said rollers into engagement with said straight surfaces to cause said contact member to -be rocked about its pivotal mounting as said rollers traverse said surfaces from one side of said mounting to the other in response to oscillating movement of said operating lever and thereby eiect opening and closing movement of said movable contact member with a snap action.

ORVEL G. KILLIAN. BASCUM O, AUSTIN.

REFERENCES crran The following references are of record in the file, of this patent:

UNITED STATES PATENTS Number Name Date 596,457 Hailey Dec. 28, 1897 689,929 Suren Dec. 31, 1901 776,521 Levin Dec. 6, 1904 1,605,910 Appleton et al Nov. 9, 1926 2,214,695 Jennings Sept. 10, 1940 2,267,203 Krieger a Dec. 23, 1941 2,342,945 Krieger Feb, 29, 1944 2,416,169 Freese Feb. 18, 1947 FOREIGN PATENTS Number Country Date 406,437 Great Britain Mar. 1, 1934 

